[Bug 1655779] Re: udev deletes and recreates partition devices when the disk is opened r/w

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: systemd (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1655779

Title:
  udev deletes and recreates partition devices when the disk is opened
  r/w

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  Description:	Ubuntu 16.04.1 LTS
  Release:	16.04

  parted:  3.2-15
  gparted:  0.25.0-1

  
  Applications that utilized parted/libparted to probe for block device information disable the read only status during the probe.

  Example:

  Set a block device read only using either hdparm -r1 /dev/sdc* or blockdev --setro /dev/sdc*:
  # hdparm -r1 /dev/sdc*

  /dev/sdc:
   readonly      =  1 (on)

  /dev/sdc1:
   readonly      =  1 (on)

  
  Run gparted

  
  Check the readonly status with hdparm:
  # hdparm -r /dev/sdc*

  /dev/sdc:
   readonly      =  0 (off)

  /dev/sdc1:
   readonly      =  0 (off)

  
  The read only status has changed to off.  This can be replicated using partprobe:

  Set a block device read only using either hdparm -r1 /dev/sdc*:
  # hdparm -r1 /dev/sdc*

  /dev/sdc:
   readonly      =  1 (on)

  /dev/sdc1:
   readonly      =  1 (on)

  
  Probe the devices using partprobe -s:
  # partprobe -s
  /dev/sda: msdos partitions 1 2 3
  /dev/sdb: gpt partitions 1 2 3 5 4
  /dev/sdc: msdos partitions 1

  
  Recheck the read only status:
  # hdparm -r /dev/sdc*

  /dev/sdc:
   readonly      =  0 (off)

  /dev/sdc1:
   readonly      =  0 (off)

  
  As before the read only status has been switched off.  Again, this can be replicated using parted:

  Set a block device read only using either hdparm -r1 /dev/sdc*:
  # hdparm -r1 /dev/sdc*

  /dev/sdc:
   readonly      =  1 (on)

  /dev/sdc1:
   readonly      =  1 (on)

  
  List the partition layout using parted -l:
  # parted -l
  .
  .
  Model: WDC WD10 EFRX-68JCSN0 (scsi)
  Disk /dev/sdc: 1000GB
  Sector size (logical/physical): 512B/512B
  Partition Table: msdos
  Disk Flags: 

  Number  Start   End     Size    Type     File system  Flags
   1      1049kB  1000GB  1000GB  primary  ntfs

  
  Recheck the read only status:
  # hdparm -r /dev/sdc*

  /dev/sdc:
   readonly      =  0 (off)

  /dev/sdc1:
   readonly      =  0 (off)

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